Insulating material in gel form



Patented Jan. 3, 1939 INSULATING MATERIAL INGEL FORM William C. Ferguson, St. Louis, Mo.

No Drawing. Application May 6, 1935, Serial No. 20,059

4 Claims.

This invention relates to an insulating material in gel form, and with regard to certain more specific features, an insulating mastic adapted to be applied to surfaces to be insulated either by means of troweling or, preferably, by squirting it on with a gun.

Among the several objects of the invention may be noted the provision of an insulating material of the class described which, when in condition for apphcation has a fluidity or plasticity permitting of its ready application to surfaces either by troweling or by squirting it through a gun; an insulating material of the class described which has an unusually high proportion of cork or like content, but which is not likely to separate upon standing into layers of different compositions; the provision of an insulating material of the class described which, when used, has great adhesive value for the surface to which it is applied; the provision of an insulating material of the class described, which after application, is resistant to reasonably high temperatures and is flexible and resilient to an optimum extent; and the provision of an insulating material which is both economical in manufacture and use. Other objects will be in part obvious and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, and features of composition and synthesis, which will be exemplified in the products hereinafter described, and the scope of the application of which will be indicated in the following claims.

Briefly described, the present invention comprises a mastic or semi-plastic, semi-fluid mass, which comprises a comminuted material having insulating properties in itself, such as ground cork, together with a binder or flux agent which binds the mass together and gives it fluidity. The cork or similar material is, however, the material which provides the primary insulating quality. A principal feature of the mixture comprising the present invention is that it is so compounded and it has such a viscosity or fluidity that it may be squirted through a gun or the like, under the pressure of compressed air, in the course of its application to a surface to be covered therewith.

The problems involved in compounding a mixture of this sort are many. First, the material in order to shoot has to be a liquid which will flow under pressure in a hose and pass out through an air gun. This means that the voids between particles of cork and the like have to be more or less filled with a liquid material in order to make the entire mass fluid. However,

it will be understood that if ground cork is introduced into the average liquid, the cork Will immediately float to the top of said liquid and 5 form an upper layer of dry, sandy type which will key together and not flow through a hose and gun.

The present invention overcomes this difliculty by providing a liquid which not only holds the 10 ground cork in suspension uniformly, but acts as a binder for the cork as it is projected against, and hits, the surface to be insulated. This binder is of the character of an asphaltic gel. It is well known that certain asphalts have the char- 15 acteristic when mixed with diluents, of forming a gel, or livering. In the present invention, this gel characteristic is made use of. It has a high percentage of volatile diluent content. When mixed with cork, it has a tendency to 20 hold the cork in suspension as it is not completely a liquid, but a gel. This prevents the settling out of the cork particles and maintains the insulating materialin a mass of uniform composition for great lengths of time. 5

However, in order to further prevent the floating of the cork in such a liquid or gel, it is desirable that there be introduced a small percentage of a fibrous material, such as asbestos fibre or cotton linters. 'When such fibrous material is mixed into the liquid, it forms a mastic, which when the cork is introduced, locks the particles of cork between the fibres of asbestos. The heavy specific gravity of the asbestos fibres helps to hold the cork particles in suspension in a homogeneous mass, which will not separate. The liquid, or gel portion of this mastic, is present in sufiicient volume to substantially fill the voids and provide a liquid which will flow through a hose and a gun under pressure. 0

One specific example of a mixture made up in accordance with the present invention is as follows:

A refined, blown asphalt having a penetration of 10 to 12, and a melting point of the order of 220 F., is chosen. This asphalt is warmed to such a point that it is thoroughly softened. Into it is then worked a diluent which may comprise a petroleum naphtha of the rubber-solvent type, having a 68 to '70 gravity and aflash point below 20 F. When the diluent is added to the point that it is present to approximately twice the weight of the asphalt, and the mixture is allowed to set, say overnight, a thin jelly-like material is obtained, which is the basis for the mixture. 55

The next step comprises adding asbestos fibre to the asphalt gel. A proportion of 17.8 asbestos fibre to 76.0 asphalt gel, by weight, has been found satisfactory. After the asbestos fibre is thoroughly worked in, it is time to add the cork. The cork preferably comprises particles which range from 8 mesh to 200 mesh in size. The cork is worked into the asphalt gel-asbestos fibre mixture, prepared as above, and in the ultimate mix, the cork comprises approximately 6.2 parts by weight as against the 17.6 parts of asbestos fibre and '76 parts of asphalt gel. It will be understood that while the cork represents but a small portion of the final mix, when considered by weight, that the 6.2 parts by weight amounts to about 82.5 per cent of the mixture by volume, after the material has been applied and the diluent has evaporated.

The mixture as thus prepared is perfectly stable, that is to say, the cork exhibits no tendency to settle out or form a layer'on top. This is true over many months of standing. It is quite liquid and can be readily worked with a stick or the like. 'It is also so fluid that it may be carried under pressure through a hose and projected through a gun.

The preferred method of applying this insulating material comprises squirting it onto the sur-' face to be insulated through a gun of the general type used in spray-painting, under the pressure of compressed air. When this procedure is used, there is a strong tendency for the diluent to evaporate between the point that the material leaves the nozzle of the gun and the point that it hits the surface to which it is being applied. This means that the liquidity of the material is maintained as long as it is in the hose and gun, but by the time it hits the wall, it becomes a sticky, semi-solid mass which will not readily fiow. This is distinctly advantageous as it means that the material will adhere firmly to the surface on which it is applied, Without slipping or slumping. It has been found possible, with a mixture having the composition as described above, to successfully apply in one operation, a layer of material up to two inches in thickness on a vertical wall without its slumping or slipping from the surface of the wall, but maintaining its thickness uniform throughout the area to which it is applied.

After a short period of drying to dispose of the small portion of diluent remaining in the material, it will be found to comprise a layer of high insulating qualities. It is a comparatively open structure consisting primarily of cork granules coated with asphalt and bound together with asbestos fibre which is likewise coated with asphalt. It has an insulating value, or thermal efiiciency, almost equal to that of cork board. It withstands temperatures up to the melting point of the asphalt used without losing its semi-rigid character. Further, it has a resilience or give that makes it resistant to structural shocks.

A particularly efiicient method of applying the liquid insulating material to the surface to be covered, comprises squirting it through a gun with compressed air, the air being heated. When heated air is thus used, the tendency to evaporate the volatile between the time the material leaves the nozzle of the gun and it'hits the surface to which it is being applied, is greatly enhanced. This means that by the time the material impacts against the surface, it is substantially freed of all of its volatile diluent content. The use of a heated blast of air in this manner also permits the material to be made up with a volatile or diluent of much heavier character than the naphtha heretofore described. This effects an economy in production inasmuch as the light naphtha referred to above is a comparatively expensive item.

The material of the present invention is also 1 adapted for application to the surface to be insulated by means of a trowel or other handworking means. However, in this instance, it must be applied in a series of thin layers and opportunity given for each of the said layers to dry or give up their volatile content before the next layer is applied. If this procedure is not adopted, the fluidity of the material causes it to slump or slip on the surface to which it is being applied.

While the foregoing description has been concerned primarily with cork as the insulating material content of the mixture it will be apparent that the invention is not so limited. For example, the cork may be replaced by sawdust, or by Zonolite, which is a mica product. Such materials likewise are held in substantially permanent suspension in the asphaltic gel described.

Under some circumstances, the asphalt may be replaced by a resin, which has many properties similar to asphalts and useful in this type of mixture.

It is to be understood that the ingredients and proportions of the ingredients given in the specific example heretofore described, are by way of example only and are not limitations upon the scope of the invention. For instance, many other asphalts or resins, other diluents or other materials may be used in widely varying proportions with results that are satisfactory to a greater or less degree.

As many changes could be made in carrying out the above compositions without departing from the scope of the invention, it is intended that all matter contained in the above description shall be interpreted as illustrative and not in a limiting sense.

I claim:

1. An insulating material in gel form comprising a binder consisting of an asphalt gel, with a volatile diluent, and comminuted cork substantially permanently suspended in said binder.

2. An insulating material in gel form comprising a binder consisting of an asphalt gel, with a volatile diluent, and comminuted solid material having insulating properties per se substantially permanently suspended in said binder.

3. An insulating material in gel form comprising a binder consisting of an asphalt gel, with a volatile diluent, and comminuted cork and asbestos fiber substantially permanently sus- 

